Conventional data processing systems may provide digital signal processing capabilities for converting an analog signal into digital form. When sampling an analog signal, such as audio, to convert it into digital form for storage, the number of samples taken per second (sampling rate) determines the quality of the signal that is generated when the digital signal is converted back to an analog form. According to the Nyquist Theorem, a band-limited analog signal, x(t), can be reconstructed from its sample values, x(nT), if the sampling rate, 1/T, is greater than twice the highest frequency, f, present in x(t). The sampling rate, 2*f, is referred to as the Nyquist rate.
The sampling rate in a conventional data processing system is either determined by the designer or is left to the user to decide. If a sampling rate smaller than the Nyquist rate is chosen (undersampling), information will be lost from the original analog signal, decreasing the fidelity of the digital signal when it is played back. oversampling (selecting a sampling rate much higher than the Nyquist rate), on the other hand, will cause the sampling rate of the sampled signal to be larger than what is needed to reconstruct the signal from its samples, thus wasting valuable storage space. Conventional systems do not determine the Nyquist rate of the analog signal, and thus can not prevent the information loss caused by undersampling or the storage waste caused by oversampling. This problem is compounded in a multimedia data processing system which may be converting multiple analog signals, all with differing Nyquist rates.
The prior art approaches present the user with seven difficulties. The first difficulty is that the prior art approaches do not automatically determine the Nyquist rate of an analog signal. The second difficulty is that the prior art approaches do not automatically determine a sampling rate for an analog signal based on the analog signal's Nyquist rate. The third difficulty is that the prior art approaches do not inform a user that a loss of information due to undersampling may occur. The fourth difficulty is that the prior art approaches do not inform a user that a waste of storage due to oversampling may occur. The fifth difficulty is that the prior art approaches do not provide a user a choice of alternative actions when such a loss of information or a waste of storage may occur. The sixth difficulty is that the prior art approaches do not adjust a sampling rate to prevent either a loss of information or a waste of storage. The seventh difficulty is that the prior art approaches do not adjust a sampling rate to available storage.
Thus the prior art provides no method of, or apparatus for, automatic detection of potential information loss due to undersampling and automatic detection of potential storage waste due to oversampling based on automatic detection of an analog signal's Nyquist rate. As such, there is a need for a method of, and apparatus for, providing automatic detection of potential information loss due to undersampling and automatic detection of potential storage waste due to oversampling based on automatic determination of an analog signal's Nyquist rate.